<section id="headings">
  <h2>Headings</h2>
  <h1>Heading Level 1</h1>
  <h2>Heading Level 2</h2>
  <h3>Heading Level 3</h3>
  <h4>Heading Level 4</h4>
  <h5>Heading Level 5</h5>
  <h6>Heading Level 6</h6>
  <hgroup>
    <h2>Heading level 2 within hgroup</h2>
    <h3>Heading level 3 within hgroup</h3>
  </hgroup>

  <details class="demo">
    <summary>View code</summary>
    <pre><code>&lt;h1&gt;Heading Level 1&lt;/h1&gt;
&lt;h2&gt;Heading Level 2&lt;/h2&gt;
&lt;h3&gt;Heading Level 3&lt;/h3&gt;
&lt;h4&gt;Heading Level 4&lt;/h4&gt;
&lt;h5&gt;Heading Level 5&lt;/h5&gt;
&lt;h6&gt;Heading Level 6&lt;/h6&gt;
&lt;hgroup&gt;
  &lt;h2&gt;Heading level 2 within hgroup&lt;/h2&gt;
  &lt;h3&gt;Heading level 3 within hgroup&lt;/h3&gt;
&lt;/hgroup&gt;</code></pre>
  </details>
</section>